Malaya is a narrow mountainous peninsula south of Thailand. The peninsula includes Malaysia and the small, and now independent, state of Singapore. Malaysia is situated just north of the equator and has an equatorial climate with high temperatures and an abundance of rainfall all year round. Like most of the region, it is influenced by the great Asian monsoon, with northeast winds from November to February and southwest winds from April to September.

During the transition periods between the two monsoons (usually March and September or October), winds are light and variable. This transition is associated with the movement of the Intertropical Convergence Zone. This zone of more concentrated cloudiness and precipitation travels north in March and south in October. Rainfall is enhanced during these transitions.

Singapore on the southeast tip of the Peninsula has the most rainfall during the northeast monsoon. At Kuala Lumpur, a dual maxima is more clearly seen, tied to the transition between the two monsoons.

Because of its equatorial location, temperatures are high and do not vary greatly from day-to-night or from month-to-month. The greatest temperature variation occurs with elevation. The higher elevations are much cooler than the lower elevations, yet they tend to be cloudier and wetter. Because of the surrounding tropical oceans, high humidity is a persistent element of the climate, regardless of the time of day or the season.

The combination of high temperature and humidity means muggy conditions prevail. Relief can be sought in higher elevations or near the coast with the sea breeze or strong monsoon flow during the peak monsoon seasons. During the transition seasons, because of the lighter winds, conditions are often oppressive, even at night.